This invention relates to an adapter for coupling optical fiber connectors which have ferrules, respectively.
An optical fiber connector typically includes a ferrule, which is a small cylinder and receives and holds the end of an optical fiber. In a typical connection between two optical fibers, a pair of ferrules are butted together. In order to support and hold the suitable butting of the ferrules, an adapter is used. The adapter couples two optical fiber connectors so that optical fibers held by ferrules are suitably aligned with each other. Such an adapter is disclosed in U.S. Pat. No. 5,647,043 or JP-B 3103773.
Another adapter is disclosed in JP-A H04-323607. The adapter is mounted in a backboard of an instrument. One optical fiber connector is fitted to the adapter in the inside of the instrument, wherein that connector is referred to as an internal connector. The other connector to be coupled with the connector is fitted to the adapter in the outside of the instrument, wherein that connector is referred to as an external connector. The external connector can be easily fitted with and removed from the adapter anytime. On the other hand, for removal of the internal connector, the instrument has to be opened. Therefore, the fitting of the internal connector is kept normally for a long time.
For easy maintenance of the ferrule of the internal connector, the adapter of JP-A H04-323607 comprises first and second members which are detachably coupled together. The first member is fixed to the board, while the second member is coupled to the first member. The adapter further comprises a sleeve for positioning the ferrules of the internal and the external connectors. The sleeve is held by the second member. Upon the maintenance of the ferrule of the internal connector, the second member is decoupled from the first member so that the end of the ferrule of the internal connector can be seen from the outside of the instrument.
As an improvement on the adapter of JP-A H04-323607, another adapter is disclosed in JP-B 3000342. According to JP-B 3000342, at least two second members are prepared corresponding to two types of external connectors. The adapter of JP-B 3000342 allows a user to select and change the second member depending on the type of the external connector even after the installation of the instrument.
However, there is one problem that, upon the replacement of the second member of the adapter, sometimes the end portion of the ferrule of the internal connector is not smoothly inserted into the sleeve but is undesirably brought into contact with the end of the sleeve. The undesirable contact damages the ferrule of the internal connector.